christie, a romney ally. >>> in just over a week you will be asked to decide who should be president. and you may have already cast your vote in the comfort of your own home. but did your vote count? nbc bay area's marianne favro is here in the newsroom with a look at a simple mistake people make that could get their mail-in ballot kicked out. >> reporter: the most important mistake is people forget to sign their ballot envelope. so far 179 mail-in ballots have been kicked out because of that. people make other mistakes too that prevent their votes from counting. in santa clara county, the mail-in ballots are already pouring in. 133,000 so far. an estimated 72% of all registered voters in the county are expected to mail in their ballots. but unfortunately, they won't all count. >> inconsistent, and we cannot determine that that signature from the voter, we would deny that person and that vote ballot would not be counted. >> reporter: this machine takes a picture of each signature and county staff compares it with the one when the voter registered. if they don't match, they're challen